The Happy hit went viral in an unusual way with people round the world making their own cover videos. swissinfo.ch zooms in on Swiss versions. (RTS le journal/YouTube/swissinfo.ch)
The singer Pharrell Williams talked to Swiss TV about the phenomenon while at the Montreux jazz festival.
It was his first appearance at the Swiss resort, one of Europe's most prestigious summer music festivals, whose 48th edition runs until July 19.
The soundtrack to the film Despicable Me2, which included Happy, was released in June 2013 but the song was not promoted as a single until November.
As of May 2014, more than 1,500 cover videos had been created by people around the world.
Inspired by this global phenomenon, a French couple launched a website to showcase the re-makes.
In May 2014, a group of Iranian fans who created a tribute to Happy were arrested, as the authorities considered the song unchaste.
Later the Iranian president criticized the arrest and the video producers were released.
Pharrell has had three mega hit singles and picked up four Grammy Awards. He was named the top producer of the past decade by Billboard magazine.